Eliminating degradation during bonding of gas atomized Nd-Fe-B

Author

Branagan, D.J. ; Hyde, TA ; Sellers, C.H. ; Panchanathan, V.

Author_Institution

Idaho Nat. Eng. Lab., Idaho Falls, ID, USA

Volume

33

Issue

5

fYear

1997

fDate

9/1/1997 12:00:00 AM

Firstpage

3838

Lastpage

3840

Abstract

While significant progress has been made in improving the hard magnetic properties of Nd-Fe-B powder produced by inert gas atomization, the ability to maintain the hard magnetic properties during low temperature heating, such as that experienced during bonding, has not been previously demonstrated. For all alloys studied, bulk oxidation was the primary degradation mechanism occurring at elevated temperatures (>225°C). In the rare earth rich conventional alloys, reverse domains nucleated from defects located at or near the surface are a significant degradation mechanism which occurs at low temperatures (<225°C) and severely limits bonded magnet performance. In contrast, TiC modified alloys do not experience degradation during bonding at normal bonding temperatures (150°C to 200°C) due to elimination of the surface reversal degradation mechanism. This is due to the better bulk corrosion resistance resulting from the ability to process compositions with reductions in rare earth content coupled with an internal nanocrystalline microstructure which is similar to melt-spun ribbons

Keywords

boron alloys; coercive force; corrosion; ferromagnetic materials; grain size; iron alloys; magnetic domains; magnetisation reversal; nanostructured materials; neodymium alloys; oxidation; permanent magnets; powder metallurgy; remanence; 150 to 225 degC; Nd-Fe-B; Nd-Fe-B powder; NdFeB-SiC; TiC; TiC modified alloys; bonded magnet performance; bonding; bulk corrosion resistance; bulk oxidation; compositions; defects; degradation elimination; degradation mechanism; elevated temperatures; gas atomized Nd-Fe-B; hard magnetic properties; inert gas atomization; internal nanocrystalline microstructure; low temperature heating; low temperatures; melt-spun ribbons; normal bonding temperatures; rare earth rich conventional alloys; reverse domains; surface reversal degradation mechanism; Bonding; Corrosion; Degradation; Heating; Magnetic domains; Magnetic properties; Oxidation; Powders; Surface resistance; Temperature;

fLanguage

English

Journal_Title

Magnetics, IEEE Transactions on

Publisher

ieee

ISSN

0018-9464

Type

jour

DOI

10.1109/20.619588

Filename

619588